Interlocking apparatus



Dec. 1924. 1,519,310

I c. A. JOHNSON ET AL INTERLOGKING APPARATUS Filed Oct. 8, 1920 INVENTORS WITNESSES (Ydzvmv/Zfihaozz f ATTORNEY Patented Dec. 16, 1924.

UNITED STATES 1,519,310 PATENT OFFICE.

CLARENCE A. J OHN SON, OF LARIMER, AND ERNEST K. READ, OF VJILKINSBURG, PENN- SYLVANIA, ASSIGNORS TO WESTINGHOUSE ELECTRIC AND MANUFACTURING GOM- PANY, A CORPORATION OF PENNSYLVANIA.

INTERLOCKING APPARATUS.

Application filed October 18, 1920. Serial 1%. 117,678.

To all whom it may concern:

' Be it known that we, CLARENCE A. JOHN- SON, a citizen of the United States, and a resident of Larimer, in the county of Vestmoreland and State of Pennsylvania, and ERNEST K. READ, a citizen of the United States, and a resident of VVilkinsburg, in the county of Allegheny and State of Penn sylvania, have invented a new and useful Improvement in Interlocking Apparatus, of which the following is a specification.

Our invention relates to mechanical interlocking devices which are adapted to insure proper sequence in the operation of a plurality of levers, such as are used in connection with electric-switch apparatus.

The invention is designed especially for use in connection with electric motors that require a relatively low voltage when being started and a much higher voltage to bring them up to normal running speed and to maintain that speed; and it has for its object the provision of a construction wherein theswitch that controls the low-voltage circuit must be moved to starting position 'before the switch controlling the high-voltage circuit can he closed; wherein the high-voltage circuit mustbe closed immediately after the low-voltage switch has been closed, and wherein each switehis held against closing movement while the other switch is in closed position,

In the operation of large motors which must he started under low voltage, switch isusually provided to control the low voltage circuit used in starting,- and another switch, known as the running s'w tch, is provided to control a high-voltage circuit. If the switches are not closed iii-the proper sequence, or are both in closed position at the same time, serious injury to the operator and to the electrical apparatus may result. Various types of apparatus have been adopted to prevent such accidents, but, in many of them, it is possible to start the motor and then delay the closing of the running switch until long after the starting switch has been opened and the motor has come to a stop or its speed so reduced as to make the closing of the running switch hazardous.

Our device not only insures the operation oi the switches in proper sequence but also insures against closure of the running switch after the starting switch has been opened for a period of time sufiicient to permit a material reduction in the momentum of the motor.

Figures 1, 2 and 3 of the accompanying drawing are diagrammatic front elevational views of our locking apparatus, and respectively show the positions occupied by the movable parts at various states 01. their movement.

Fig. 1 illustrates the apparatus in position above a starting handle or lever stand a running handle 5. A bar (3 is slidablv supported by a pair of fixed members 7 and has a downwardly extending guide member 8. A lever 9 is supported on a pivot 10 and has a forked extension 11 embracing the bar 6. At its upper end, the lever 9 is conuerted to a coil spring 17 and has pivotal eoimew tion with the piston 12 of a dashpot 13. IL alve 18 is provided to regulate the move ment of the piston 12 in the dashpot. The lever 9 carries also a guide member 1% which coacts with the guide 8.

Each of a pair of springs 15 and 16 has one end secured to the bar 6 and the other end engaging the fork 11.

As shown in Fig. 1, the parts are all in the released position, with the handle 1 of a starting switch and the handle 5 of a running switch both in open position, and the bar 6 lying far enough to the left to block the movement of the handle 5 into closed position. If, new, the handle at be raised to the position shown in F 2, to close the starting circuit, the guide 1 1 will be pushed to the right, thus placing spring 15 under compression and elongating the spring 17, as shown in Fig. 2.

Movement of the handle 4- from the position shown in Fig. 2 to that shown in Figs. ,r

1 and 3, will permit the compressed spring 15 to snap the bar 6 to the right and so clear the way for the raising of the handle 5 to the position shown in Fig. 8 to close the running circuit. If the handle 5 is not moved pron'iptly, the spring 17 will act, through the lever 9 and guide member 14, to return the bar 6 to the position occupied by it in Fig. 1, and the running handle cannot then be moved to close the circuit until after the starting handle is again operated. The proniptness with which the running handle 5 must be moved is dependent upon the (ill time required for the spring 1.7 to act against the retarding effect of the dashpot, and the dashpot may be so regulated that the handle 5 must be moved to closed position before. there is any substantial loss in the momentmn imparted to the motor by the starting circuit.

IVhen the parts are in the positions shown in Fig. 3, the bar 6 extends to the right far enough to block the path of closing movement of the handle at and is held in that position by the handle 5.

By reason of the engagement between the handle and the end of the bar (3, the bar is held against movement when the spring 16 is placed under compression by the lever S), on its return from the position of Fig. 2 to that of Fig. 1. Upon movement of the handle 5 trom closed, or runnin position (Fig. 3) to open. position (Fig. 1), the spring 16 snaps the bar 6 from the position occupied in Fig. 3 to that of Fig. 1.

Various modifications might be made in the arrangement of both the springs and the lovers without departing from the spirit of the invention.

Veclaim:

1. In combination with a starting-switch member and a running-switch member, an interlock member normally in position to lock the running-switch member against closing movement and to permit the starting-switch member to close, and means operated by the starting-switch member for moving the interlock member into position to lock the starting-switch member against closing movement and to permit the running-switch member to close, said means also serving to return the locking member to normal position when the running-switch member has been returned to neutral position.

2. In combination with a starting-switch member and a running-switch member, an interlock member normally in position to lock the running-switch member against closing movement and to permit the start ing-switch member to close, and means operated by the starting-switch member during a cycle of movement thereof for moving the interlock member into position to lock the starting-switch member against closing movement and to permit the running-switch member to close, said means also serving to return the locking member to normal position when the running-switch member has been returned to neutral position.

In combination with a starting-switch member and a running-switch member, an interlock member normally in position to lock the running-switch member against closing movement and to permit the starting-switch member to close, and means operated by the starting-switch member during a cycle of movement thereof for moving the interlock member temporarily into position to lock the starting-switch. member against closing movement and to permit the running-switch member to close, means for retaining the interlock member in its last named position while the rnnning-switch member is in closed position, and means for automatically returning the. interlock member to normal position when the runningswitch member is moved to neutral position.

4:. In combination with a pair of levers normally in retracted position, a movable locking member preventing either of said levers moving to advanced position while the other is advanced means operated by one lever during its cycle of movement for moving the locking member to temporary unlocked position with respect to the other lever, means for returning the locking member from its temporary position, and means governing the duration of the temporary period within which the last named lever may be moved to advanced position.

5. In combination with a starting-switch lever and a running-switch lever, a locking member for locking either lever against closing movement while the other is in closed position and normally in a position permitting the starting-switch lever to be moved to closed position and locking the runningswitch lever in neutral position, and means whereby a cycle of movement by the starting-switch lever places the locking member under tension to move it into temporary unlocked position with respect to the runningswitch lever and then return it to normal position.

6. An interlock device comprising a bar, a coil spring connected to the bar, a lever pivoted adjacent the bar and also havin engagement with the coil spring, a second coil spring connected to the lever, a handle whereby the lever is moved with respect to the bar and both of said springs placed under tension, means whereby the withdrawal of the handle permits the first named spring to move the bar to its normal position with respect to the lever, and means whereby the second coil spring serves to return both the lever and the bar to their original positions.

7. An interlock device comprising a bar, a coil spring connected to the bar, and a lever pivoted adjacent the bar and also having engagement with the coil spring, a second coil spring connected to the lever, a handle whereby the lever is moved with respect to the bar and both of said springs placed under tension, means whereby the withdrawal of the handle permits the first named spring to move the bar to its normal position with respect to the lever, means whereby the second coil spring serves to return both the lever and the bar to their original positions, and a dashpot connected to the lever for retarding the movement thereof A l i under the action of the said second coil spring.

8. In combination, in an interlock device, a starting-switch lever and a running-switch lever, means for preventing either lever from being advanced while the other lever is lying in advanced position, means Whereby the running-switch lever is held against advancement until after the starting switch lever has been advanced and retracted, and means for automatically limiting the period during which the running-switch lever may be advanced.

9. In combination, in an interlock device, a starting-switch lever and a running-switch lever, means for preventing either lever from being advanced while the other ley er is lying in advanced position, means whereby the running switch lever is held against advancement until after the starting-switch lever has been advanced and retracted, and adjustable means for controlling the period of time during which the running-switch lever may be advanced.

10. The combination with two levers, of means for automatically preventing the operation of one lever except within a predetermined period following the operation of the other lever.

In testimony whereof, We have hereunto subscribed our names this 13th day of October, 1920.

CLARENCE A. JOHNSON. ERNEST K, READ. 

